Repo Topic 2 - Male Reproduction Flashcards
How is the tunica vaginalis clinically relevant?
Excess fluid between the visceral and parietal layers = hydrocoele
Hydrocoele is usually harmless and is easily drained
How long does spermatogenesis take?
64 days
Define spermatogenesis
Process of sperm production
Immature stem cells (spermatogonia) –> mature spermatids
Describe the shape of mature spermatids
Differentiate from round to elongated
Describe the histology of the prostate
- Fibromuscular stroma
- Cuboidal/low columnar epithelial cells produce secretions - associated with prostatitis
- Eosinophillic bodies - amyloid bodies (inspissated secretion)
List the layers of the coverings of the testes
- Skin
- Dartos muscle - smooth muscle in dermis, causes wrinkling of scrotal skin
- External spematic fascia
- Cremasteric fascia and muscle - skeletal muscle, in spermatic cord, reflex
- Internal spermatic fascia
- Parietal tunica vaginalis
- Visceral tunica vaginalis
- Tunica albuginea
- Tunica vasculosa
What is the function of the ilioinguinal nerve?
Sensory innervation of the genitalia - exits at superficial ring of the inguinal canal (doesn’t go through deep ring)
Describe the histology of the seminiferous tubules
- Contractile peritubular myoid cells just outside basement membrane
- Sertoli cells inside basement membrane
- Spermatogonia on basement membrane –> spermatozoa at luminal edge
Describe the duct system of the testes
- 200-300 lobules divided by connective tissue septa with highly coiled seminiferous tubules (1-4 per lobule)
- Straight tubule (tubulus rectus)
- Rete testic
- Efferent ductules
- Epididymis - long, highly coiled tubule
- Vas deferens
Describe the shape/size of the prostate gland
Pyramidal - size and shape of a chestnut
Describe the secretions of the seminal vescicles
- Viscous alkaline fluid - neutralises acid of female reproductive tract (pH 2-3) to allow sperm to function
- Fructose - for ATP production by sperm
- Prostaglandins - contraction of female tract, aid motility and viability
Describe the venous drainage of the scrotum
Follow arteries into external pudendal vein, drains into vesical venous plexus
Where are the seminal vescicles located?
Between bladder fundus and rectum
Describe the secretions of the Bulbourethral glands
Produce mucous for lubrication - contains glycoproteins (cleans urethra)
Describe the structure of the epididymis
- Has gross form - head, body, tail
- Pseudostratified columnar epithelium with stereocilia
Define endocrine disruptors
Exogenous substances which disrupt normal endocrine function - stimulate or inhibit
What are phytoestrogens?
- Naturally occuring substances in plants e.g. genistein
- Have oestrogenic effect - may reduce fertility/protect from cancer
Describe the walls of the inguinal canal
- Anterior - aponeurosis of external oblique and internal oblique laterally
- Posterior - transveralis fascia
- Superior - transversalis fascia, internal oblique, transversus abdominus
- Inferior - inguinal ligament - thickened medially by lacuna ligament
List the contents of the inguinal canal
- Spermatic cord (males)
- Round ligament (females)
- Ilioinguinal nerve
- Genital branch of genitofemoral nerve
Describe the types of spermatogonia
- Pale/dark A and B
- Dark A undergoes mitosis to produce more dark A and pale As
- Dark A = stem cells, replace original
- Pale A matures into type B
- Type B matures into primary spermatocyte
What is the effect of anabolic steroids?
- Synthetic androgens, have mild testosterone-like effects
- Development of male secondary sex characteristics, increased performance
- Large amounts can have effect on reproductive system
- High circulating testosterone, affects negative feedback on hypothalamus/anterior pituitary
- Low testicular testosterone - testis atrophy and sterility
- Also affects other systems, kidney and liver damage
How is the pampiniform plexus specialised?
Cools venous blood
What effect do phthlalates have on development?
- Cause major reduction in testosterone and insulin 3 production by Leydig cells
- Abnormal testes development
- Low germ cell numbers and delayed differentiation
Describe the innervation of the scrotum
Anterior and lateral - anterior scrotal nerves from the genital branch of the genitofemoral nerve and ilioinguinal nerve
Posterior - posterior scrotal nerves from branches of the internal pudendal nerves and posterior femoral cutaneous nerve
List the compartments of the testes
- Tubules - seminiferous tubules
- Interstitium - contains Leydig cells
Describe the process of sperm
- Spermatogonia on basement membrane divide by mitosis to form primary spermatocytes (largest cells in germinal epithelium)
- Primary spermatocytes divide by meiosis I to form secondary spermatocytes
- Secondary spermatocytes divide by meiosis II to spermatids
- Spermatids are smaller than spermatocytes, undergo spermiogenesis and differetiate into spermatozoa
Describe the location of the testes
Held within scrotum outside the body - need low temperature for sperm
Left usually slightly lower
Describe the erectile tissue of the penis
- 2x corposa cavernosa - surrounded by tunica albuginea
- Blood sinuses which can fill with blood, separated by trabeculae of connective tissue and smooth muscle
- Ventral corpus spongiosum - urethra runs through
- Finer meshwork to prevent compression of urethra, thinner tunica albuginea
What covers the testes?
Scrotum - derived from genital swellings, fused at midline (scrotal raphe)
What is the clinical importance of the inguinal canal?
Weak point in abdominal wall, site of herniation
What is diethylstilbestrol?
- Synthetic oestrogen
- Prescribed to pregnant women - treat morning sickness, block spontaneous abortion, promote foetal growth
- Banned in early 1970s
- Affects reproductive development and causes vaginal cancer
- Not noticed until exposed children pubertal
What is the function of sertoli cells?
Nurse/supporting cells
Create blood-testes barrier - stops immune destruction of gametes
Support germ cell development
Describe the structure of Sertoli cells
- Cytoplasm extends from basement membrane to the lumen of the tubule
- Triangular/oval nuclei - contain fine sparse chromatin
Describe the arterial supply of the scrotum
Anterior and posterior scrotal arteries from the external and internal pudendal arteries
List the layers of the scrotum
- Skin
- Dartos muscle
- External spermatic fascia (Colles fascia) - from external oblique muscle
- Cremasteric fascia and muscle - from internal oblique muscle
- Internal spermatic fascia - from transversalis fascia
- Tunica vaginalis - parietal and visceral layer (parietal from peritoneum)
What is the inguinal canal?
- Short passage through the inferior abdominal wall
- Pathway for structures to pass from the abdominal wall to the external genitalia
Describe the interstitial tissue surrounding the seminiferous tubules
- Leydig cells with blood vessels - secrete testosterone
- Ovoid nuclei, contain punctate chromatin
- Cytoplasm stains pink (H+E)
List the types of endocrine disruptors
- Natural hormones released into environment e.g. sewage slurge spread on fields
- Natural chemicals produced by plants and fungi e.g. phytoestrogens - genistein
- Synthetically produced pharmaceuticals e.g. contraceptive pill
- Man-made chemicals e.g. pesticides
Describe the openings of the inguinal canal
- Deep = transversalis fascia (internal)
- Superficial = external oblique (external)
Describe the structure of the seminal vescicles
- 5cm long
- Coiled tubes
- Combines with the ductus deferens to form the ejaculatory duct, which drains to the prostatic urethra
Describe the contents of the spermatic cord
- 3 arteries
- A to ductus deferens
- Testicular a
- Cremasteric a
- 3 nerves
- Genital branch of genitofemoral n
- Sympathetic nerves - testicular n
- Ilioinguinal n (runs just outside in inguinal canal)
- 3 other
- Pampiniform plexus
- Ductus deferens
- Lymphatic vessels
Describe the path of mature spermatids after they are formed?
- Lumen of tubules
- Efferent ducts
- Epididymis
Where is the prostate gland located?
Surrounds the beginning of the urethra
How long is the ductus deferens?
45cm
Where are the layers of the scrotum derived from?
Formed by the layers of the anterior abdominal wall
Describe the structure of the ductus deferens
- Thick-walled tube
- Part of spermatic cord, passes through the inguinal cana;
- Smooth muscle in wall contracts (peristalsis) for ejaculation
- Runs on lateral wall of pelvis
- Attached at ampulla to seminal vescicle - outpouching of ductus
Describe the regulation of spermatogenesis
- Gonadotrophin releasing hormone from hypothalamus stimulates relase of LH and FSH from anterior pituitary
- LH causes leydig cells in testis to make testosterone
- Testosterone and FSH stimulate sertoli cell function to support developing germ cells in spermatogenesis
- Once spermatogenesis reaches sufficient level, sertoli cells produce inhibin
- Limits FSH production
- Spermatogenesis decreases
Describe the structure of the ductus deferens
- 3 muscle layers - inner longitudinal, middle circular, outer longitudinal
- Pseudostratified columnar epithelium with stereocilia
Describe the parts of the male reproductive system
- Paired gonads - testes
- Duct system - closely associated with urinary sytem (share final duct - urethra)
- Epididymis, ductus deferens, urethra (within penis)
- Accessory glands - prostate, paired seminal vesicles, paired bulbourethral glands
Where are the bulbourethral glands located?
Pea-sized around base of prostate
Are sperm haploid or diploid?
Haploid
Describe the structure of the tunica vaginalis
- Closed sac of peritoneum
- Visceral and parietal layers - space between contains peritoneal fluid
Describe the lining of the bulbourethral glands
Columnar epithelium
What is the function of the testes?
- Exocrine - gametes
- Endocrine - mainly testosterone
How is spermatogenesis regulated?
- Gonadotrophin releasing hormone from the hypothalamus causes release of FSH and LH from the anterior pituitary
- LH causes Leydig cells to produce testosterone
- Testosterone and FSH stimulate the Sertoli cells to support developing gametes
- When spermatogenesis reaches sufficient level, sertoli cells also produce inhibin
- Limits FSH production
- Decreases spermatogenesis
Describe the cremasteric reflex
- Contraction of the cremaster muscle to raise the testes
- For protection or to shelter from cold temperature
Describe the secretions of the prostate gland
- Slightly acidic
- Citrate for ATP production
- Acid phosphatase and proteolytic enzymes - liquify coagulated semen
- Passes secretion to the urethra via prostatic ducts
What is the function of the epididymis?
- Site of maturation of sperm
- Can monitor/adjust fluid concentration and composition
- Stereocilia increase the surface area for absorption of fluid - if ejaculation doesn’t occur can be reabsorbed
Describe the coverings of the spermatic cord
External spermatic fascia, cremaster muscle and fascia, internal spermatic fascia
Describe the venous drainage of the testes
Pampiniform plexus, drains to testicular vein
Testicular vein drains to inferior vena cava on the right and the renal vein in the left
Describe the arterial supply of the testes
Testicular artery, branch of the abdominal aorta from just below the renal artery
What are phthalates?
- Man-made chemicals
- Soften and increase flexibility of polyvinyl plastics
- Potentially pose risk to male infant development
List the types of male germ cells
- Immature spermatogonia - basal (immature)
- Spermatocyte - primary and secondary
- Mature spermatid - closer to lumen, round and elongated
Define testicular dysgenesis syndrome
- Cryptorchidism, hypospadias, infertility, germ cell cancer etc.
- All symptoms linked, all are risk factors for each other
- Common origin in foetal life
- Irreversible - can treat symptoms but not cure
- Leydig cells - hypospadias and cryptorchidism
- Sertoli cells - germ cell cancer and low semen quality
What type of cells are Sertoli cells?
Somatic cells, also known as Sustinacular cells
Describe the structure of mature spermatids
- Tail for propulsion
- Midpeice contains mitochondria to produce energy
- Acrosome - cap over head, contains enzymes to penetrate egg
- Cytoplasmic remodelling - gives off residual body (phagocytosed by Sertoli cells) so mature have very little cytoplasm
- Nucleus compacts
What is the function of the genital branch of the genitofemoral nerve?
- Cremaster muscle and anterior scrotal skin in males
- Skin of mons pubic and labia majora in females
What effect do endocrine disruptors have on reproduction?
- Reduce fertility
- Developmental abnormalities
- Menstrual problems
- Early puberty
- Brain/behavioural problems
- Cancers
